This project aims to develop a novel platform that would help accelerate the development of novel antibody- based therapeutics. Numerous antibody therapies undergoing clinical trials are concerned with immunological and oncological targets. The proposed project is innovative and differs from previous studies by using deep sequencing to yeast display to systematically screen antibodies binding different epitopes on therapeutically relevant target proteins. Our technology generates unprecedented sequence-function maps that cover the entire sequence of protein binders [1]. We hypothesize that this same method can be used to develop rapid fine epitope maps of antibody-antigen interactions. Thus, the overall goal of the project is to develop the deep scanning methodology on proteins target proteins whose structures or active domains are currently unknown. To demonstrate that our novel platform can identify functional antibodies that target such proteins, we will evaluate their ability to inhibit the function of TROP2 (a.k.a tumor-associated calcium signal transducer 2, TACSTD2), our model protein, from promoting growth and metastasis. The project involves two aims. The first aim is to develop a novel epitope mapping strategy that couples yeast display with deep sequencing to generate unprecedented sequence-function maps of protein binders. The second aim will develop and screen potential novel antibodies to TROP2 for their ability to inhibit cell proliferation and metastasis through in vitro and in vivo experiments. Completion of this project will provide a platform that can identify functional antibodies that inhibit the activty of target proteins for which structures are not available. The proposed methodology will aid in the discovery and development of new therapeutics not only for cancer but other diseases, including autoimmune diseases that are amendable to antibody therapeutics.